java 二叉树_二叉树java-优快云博客

本文链接：https://blog.youkuaiyun.com/moyinghui/article/details/53438682

先感慨下：虽为通信工程毕业，但课程比较传统，偏向于运营商方向，因为历史上来说本院曾经是‘某某邮电学院’，邮电部直属院校五所之一，所以比较传统。《数据结构与算法》没怎么学过，不想最后大部分同学去了运营商或者邮电规划建设部门，我却做了android开发，基础之薄弱真是令我汗颜。虽然平时开发过程中没什么大的感知，但是我知道，如果不补上这一块，差距将一直存在。

说实话，‘树’的概念，是我毕业一年以后才知道的，囧。当时被华为的面试官鄙视的一塌糊涂。当时不以为意，也没有进行学习，直到最近希望有些改变，渐渐开始学习这些知识。

public class Tree {
    /*************************************************/
    /*********************** start *******************/
    /*************************************************/
    public static int[] array = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

    public Tree() {

    }

    /**
     * 把数组变成二叉树
     */
    public static ArrayList<Node> sortF() {
        ArrayList<Node> list = new ArrayList<Node>();
        for (int i = 0; i < array.length; i++) {
            list.add(new Node(array[i]));
        }

        for (int parentNodeIndex = 0; parentNodeIndex < array.length / 2 - 1; parentNodeIndex++) {
            if (list.get(2 * parentNodeIndex + 1) != null) {
                list.get(parentNodeIndex).leftChildNode = list.get(2 * parentNodeIndex + 1);
            }
            if (list.get(2 * parentNodeIndex + 2) != null) {
                list.get(parentNodeIndex).rightChildNode = list.get(2 * parentNodeIndex + 2);
            }
        }
        //the last parentNode
        int lastParentNodeIndex = array.length / 2 - 1;
        if (list.get(lastParentNodeIndex * 2 + 1) != null) {
            list.get(lastParentNodeIndex).leftChildNode = list.get(lastParentNodeIndex * 2 + 1);
        }
        if (array.length % 2 != 0) {
            if (list.get(lastParentNodeIndex * 2 + 2) != null) {
                list.get(lastParentNodeIndex).rightChildNode = list.get(lastParentNodeIndex * 2 + 2);
            }
        }

        return list;

    }

    public static void printNodeValue(Node node) {
        System.out.println("printNodeValue--node.selfValue=" + node.selfValue);
    }

    public static void test() {
        ArrayList<Node> list = sortF();
        System.out.println("printNodeValue=====left=====");
        leftTraversal(list.get(0));
        System.out.println("printNodeValue======mid====");
        midTraversal(list.get(0));
        System.out.println("printNodeValue======right====");
        rightTraversal(list.get(0));
    }

    /**
     * 递归实现前序遍历
     */
    public static void leftTraversal(Node p) {
        if (p != null) {
            printNodeValue(p);
            leftTraversal(p.getLeftChildNode());
            leftTraversal(p.getRightChildNode());
        }
    }


    public static void midTraversal(Node p) {
        if (p != null) {
            midTraversal(p.getLeftChildNode());
            printNodeValue(p);
            midTraversal(p.getRightChildNode());
        }
    }

    public static void rightTraversal(Node p) {
        if (p != null) {
            rightTraversal(p.getLeftChildNode());
            rightTraversal(p.getRightChildNode());
            printNodeValue(p);
        }
    }

    public static int[] initData() {
        int[] a = new int[10];
        for (int i = 0; i < 10; i++) {
            a[i] = i;
        }
        return a;
    }

    public static class Node {
        int selfValue;
        Node leftChildNode;
        Node rightChildNode;

        public Node(int self) {
            this.selfValue = self;
        }

        public Node getRightChildNode() {
            return rightChildNode;
        }

        public void setRightChildNode(Node rightChildNode) {
            this.rightChildNode = rightChildNode;
        }

        public int getSelfValue() {
            return selfValue;
        }

        public void setSelfValue(int selfValue) {
            this.selfValue = selfValue;
        }

        public Node getLeftChildNode() {
            return leftChildNode;
        }

        public void setLeftChildNode(Node leftChildNode) {
            this.leftChildNode = leftChildNode;
        }
    }
}

12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue=====left=====
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=0
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=1
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=3
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=7
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=8
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=4
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=9
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=2
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=5
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=6
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue======mid====
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=7
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=3
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=8
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=1
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=9
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=4
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=0
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=5
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=2
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=6
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue======right====
12-02 20:06:29.647 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=7
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=8
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=3
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=9
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=4
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=1
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=5
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=6
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=2
12-02 20:06:29.648 11102-11102/com.example.bxh.sayhello I/System.out: printNodeValue--node.selfValue=0